Detection instrument for plutonium-americium

Abstract

A plutonium-americium detection instrument having an end window type photomultiplier tube supported in a light weight aluminum housing. An europium activated calcium fluoride scintillation crystal coupled directly to the face plate of the photomultiplier tube with a silicone optical coupling grease. An aluminum window is supported on a styrofoam support and positioned adjacent to said scintillation crystal.

I claim: 
     
       1. An apparatus for detecting the normal radiation from plutonium-americium, comprising: a non-radioactive metal housing; an end window type photomultiplier tube; means for supporting said photomultiplier tube within said housing; a europium activated calcium fluoride scintillation crystal directly coupled to said photomultiplier tube; a light impervious, reflective, electrostatic shield on the side of said scintillation crystal remote from said photomultiplier tube; a shock absorbent layer on the side of said light impervious, reflective, electrostatic shield, remote from said scintillation crystal; means secured to said housing for retaining said shield within said housing; a radioactive contamination barrier layer on the side of said shock absorbant layer, remote from said scintillation crystal; means for supplying power to said photomultiplier tube and means, for indicating the level of plutonium-americium electromagnetic emission reaching said detection instrument. 
     
     
       2. The device as recited in claim 1 wherein a face plate forms the end window of the photomultiplier tube; said scintillation crystal being coupled directly to said face plate with optical coupling grease; said light impervious, reflective, electrostatic shield being a thin sheet of aluminum supported on the side of said shock absorbant shield adjacent said scintillation crystal. 
     
     
       3. The device as recited in claim 1 wherein said light impervious, reflective, electrostatic shield includes a layer of aluminum vacuum deposited on said scintillation crystal and an electrically conductive black paint coated over the aluminum layer. 
     
     
       4. The device as recited in claim 3 wherein said europium activated calcium fluoride scintillation crystal forms the face plate of said photomultiplier tube.